Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf] • Hacker News Board

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#101

Post by berntb » Sat, Oct 15, 2016, 1:15 PM UTC

dalke wrote: post #98

berntb wrote: post #57

Earlier quoted context omitted.

It is a theoretical "can". :-) It will be a long time before anyone use a fraction of C inside the solar system. Interstellar flight is a problem after we have gotten to a reasonable cost/kg for both launching from the Earth and for interplanetary travel. I doubt there will be a pressing need for getting close to even 100 km/s in the inner solar system for decades. (Yes yes, "640K is enough for anyone". :-) ) (Consid…

"I doubt there will be a pressing need for getting close to even 100 km/s in the inner solar system for decades" Quoting https://en.wikipedia.org/wiki/Solar_Probe_Plus : > Solar Probe Plus or Solar Probe+, previously NASA Solar Probe, is a planned robotic spacecraft to probe the outer corona of the Sun. ... As the probe passes around the Sun, it will achieve a velocity of up to 200 km/s (120 mi/s) at that time making…

He he, point. But a probe doing multiple gravity assists to get close to the sun is different from going from point A to point B -- and stopping at B. :-)

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#102

Post by simonh » Sat, Oct 15, 2016, 8:14 PM UTC

snrplfth wrote: post #53

simonh wrote: post #43

Earlier quoted context omitted.

On the other hand if we'd gone all-in on nuclear pulse launchers, there would have been no incentive for companies like SpaceX and Blue Origin to develop reusable conventional rockets which will hopefully achieve the same result at lower environmental and perhaps also financial cost.

Even if you had effective nuclear pulse propulsion, you'd still need reusable chemical launchers to get them off the surface of Earth. Nuclear pulse engines are generally not something that you start up inside an atmosphere, for both safety and efficiency reasons.

The post I was responding to strongly implied using these for launches.

> ..It would also allow us to practically ship up enough materials to build self-sustaining habitats in near space..

Re: Nuclear Pulse Propulsion – Orion and Beyond (2000) [pdf]

#103

Post by simonh » Sat, Oct 15, 2016, 8:15 PM UTC

maverick_iceman wrote: post #76

simonh wrote: post #43

Earlier quoted context omitted.

On the other hand if we'd gone all-in on nuclear pulse launchers, there would have been no incentive for companies like SpaceX and Blue Origin to develop reusable conventional rockets which will hopefully achieve the same result at lower environmental and perhaps also financial cost.

How can chemical rockets with ~3km/s exhaust velocity ever achieve the same result? Also if we had gone all in on this concept maybe today SpaceX and BO would be working with a much more promising technology.

It depends how reusable nuclear launchers would be. A less efficient launch system in terms of ISP that uses thousands of times cheaper fuel and e.g. is 10 times more reusable might be very competitive.